Scope Levels- Why?

[J E Custom]

Everyone must realize that the rifle "and" the scope must be level to each other. The line of bore and the line of site form a triangle and the hypotenuse must be vertical to the line of bore (The base of the triangle) this triangle Must be vertical to avoid error. If ether one is not level with the other. The whole exercise is a wast of time.

When setting up a scope level you must first level the rifle. (The guide rails are one of the ways to get the rifle level) Then level the recital Optically, or with a plum line, And then install the scope level and verify that the other levels are still correct and set the scope level. the scope level should be the last to set.

Then if you wan't go one step farther, go to the range and fire a 3 shot group at a vertical line at 100 yards and adjust the recital for 200, 300, 400, 500, 600 and so on firing 3 shots and aiming at the same point of aim. find the center of each group and draw a line through the center and if it is not vertical it will be an indication that something is not right.

Don't forget Spin Drift will effect the windage depending on the right or left hand barrel twist. But it will have little effect at closer distances. 600 to 1000 yards+ it will become obvious. (A good rule of thumb is about 1 MOA at 1000 yards.

J E CUSTOM

 

[LRNut]

Your barrel has no clue or preference at what angle it is shot at. Reticle is the only thing that needs to be level. You can shoot your stock at a 45 degree angle if the reticle is level. Just think about it for a second.

Your example is extreme, but it would matter. The rifle bbl is now offset horizontally with respect to the scope reticle. If you zero at 100 yards (make it 200, I don't care) the bullet is traveling up and to one side (right or left). At ranges past the zero distance, the bullet is going to diverge horizontally as well.

 

[TBell]

Don't think anyone one misunderstood. Your physics is off a bit.

you should level your receiver (centerline of barrel) to the scope reticle. If you cant the reticle, to off center line is barrel dead center, even if held the same each time which (is close to impossible), as you follow up the vertical reticle it will absolutely through your trajectory off either left or right, depending on the direction and degree of can't. Add to that, slightly low in elevation too. Now if your shooting, inside 400 yards it may not matter a lot, but out at 6- 700 or a 1000 yards it turns to inches depending on what degree of cant you have.

 

[LRNut]

Everyone must realize that the rifle "and" the scope must be level to each other. The line of bore and the line of site form a triangle and the hypotenuse must be vertical to the line of bore (The base of the triangle) this triangle Must be vertical to avoid error. If ether one is not level with the other. The whole exercise is a wast of time.

When setting up a scope level you must first level the rifle. (The guide rails are one of the ways to get the rifle level) Then level the recital Optically, or with a plum line, And then install the scope level and verify that the other levels are still correct and set the scope level. the scope level should be the last to set.

Then if you wan't go one step farther, go to the range and fire a 3 shot group at a vertical line at 100 yards and adjust the recital for 200, 300, 400, 500, 600 and so on firing 3 shots and aiming at the same point of aim. find the center of each group and draw a line through the center and if it is not vertical it will be an indication that something is not right.

Don't forget Spin Drift will effect the windage depending on the right or left hand barrel twist. But it will have little effect at closer distances. 600 to 1000 yards+ it will become obvious. (A good rule of thumb is about 1 MOA at 1000 yards.

J E CUSTOM

Good advice and essentially how I do it. I would add I zero my rifles at 500 to minimize spin drift, then enter in an offset at 200 yards (my reference zero) in SIG Kilo 2400 ABS to account for that. This minimizes spin drift but it is still about 1/2 MOA at 1200 yards. Aerodynamic jump is also something to consider.

 

[LRNut]

Here is a story I wrote for American Hunter:

An Official Journal Of The NRA | How to Level a Scope Reticle and Why It Matters

Many hunters try to eke out the last vestiges of accuracy for their favorite hunting rifles by switching bullets, playing with optimal seating length and other standard techniques. But what if I told you that you're potentially throwing away .2 to 1.2 MOA because your scope is not aligned perfectly?

www.americanhunter.org

 

[TBell]

Your example is extreme, but it would matter. The rifle bbl is now offset horizontally with respect to the scope reticle. If you zero at 100 yards (make it 200, I don't care) the bullet is traveling up and to one side (right or left). At ranges past the zero distance, the bullet is going to diverge horizontally as well.

But if you think about it for two or three seconds you understand the flaw in that reasoning. See above post

 

[26Reload]

I never knew any old framers that didn't use a level after 40 years of practice. But.......

I installed $65000 worth of paint grade cabinets in a brand new house last year.......first set in the laundry room...exterior wall leaned out 1.5" in 9'.....other side of cabinet leaned the same....maybe they built thise two,walls,on a warm day and although they were level..the wood followed the warmth of fhe afternoon sun....much like a bucks antlers.....
And the walls didn't get any better.......i didn't mind hacking up those paint grade cabinets to fit a house built so crappy...but at least the cabinets fit and were trued.......the owner of fhe house is a big time contractor...maybe he was cutting corners.............pun intended.....

 

[An Idahoan]

I used to be convinced that bore, optical axis, and reticle all had to be "in line" on mathematical/geometric grounds. I insisted despite my mechanical engineering brother telling me I was wrong. I should have listened to him. But then I finally figured it out for myself. Those whose natural point of aim involves holding the rifle at anything other than 12 o' clock can rest easy. I am one such person.

The fine print is that for those who cant the stock more than a small amount should calculate the horizontal distance between the bore and the optical axis. For example, a 2" vertical separation and a 15° left stock cant (which is a lot) will give you a 0.53" horizontal distance between the two axes. Ideally, your windage zero would be at an infinite distance, but that isn't realistic for several reasons. You can perform a windage zero at 100 yards and adjust windage so that you're right by 0.53". This way, you'll be off 0.53" at all distances, which is acceptable to 99.9% of us on this forum. If you don't offset your windage, then (assuming your reticle is still plumb) you'll be dead on at 100 yards, and left 0.53" at 200 yards, left 1.06" at 300 yards, 1.59" at 400 yards and so on.

 

[Mram10us]

I used to be convinced that bore, optical axis, and reticle all had to be "in line" on mathematical/geometric grounds. I insisted despite my mechanical engineering brother telling me I was wrong. I should have listened to him. But then I finally figured it out for myself. Those whose natural point of aim involves holding the rifle at anything other than 12 o' clock can rest easy. I am one such person.

The fine print is that for those who cant the stock more than a small amount should calculate the horizontal distance between the bore and the optical axis. For example, a 2" vertical separation and a 15° left stock cant (which is a lot) will give you a 0.53" horizontal distance between the two axes. Ideally, your windage zero would be at an infinite distance, but that isn't realistic for several reasons. You can perform a windage zero at 100 yards and adjust windage so that you're right by 0.53". This way, you'll be off 0.53" at all distances, which is acceptable to 99.9% of us on this forum. If you don't offset your windage, then (assuming your reticle is still plumb) you'll be dead on at 100 yards, and left 0.53" at 200 yards, left 1.06" at 300 yards, 1.59" at 400 yards and so on.

Your brother should test his theory. Go mount a scope canted a bit. Zero at 100. Shoot 3 shots. Run up 20moa on same target. Shoot 3 shots.

 

[blvette75]

1st introduction to a bubble level was Gunwerk's LRU, instructor made it easy to understand the value it would make in long range shooting application. Instructor was more than qualified, Retired Marine Scout Sniper with experience in "Spec Ops." He demonstrated what a canted and un-canted rifle would do at ranges from 100 to 1200 yards. Proof was in the pudding at that point!

When talking about precision anything, your strongest link is only as good as your weakest link. Bubble levels are relatively inexpensive and can make a good shooter a great shooter the first time they put the bubble level to use. Knowing this product exists and it cost less than a box of shells, why wouldn't we put a bubble level on any and all shooting platforms that we intend to be precise with?

Each to their own, but in this case it seems to be ignorant to not use a bubble level when shooting at long range!?!?

Thanks for your response, I recently gotten back into medium and long range shooting, a few years ago. Due to my inability to shoot more than 1-2 times a month, less in bad weather, or this covid-19 issue that has closed my range down for two months now, I agree with your assessment. My hunts are pricey endeavors now and the cant issue is one variable that I can address fairly inexpensively with the bubble levels, I have put them on all of my hunting rifles and now use an Atlas bipod for hunts. Is the bubble level perfect nope, but it keeps my repeatability in check(due to my previously undetected cant issues, was I canting repetitively the same, sometimes), plus teaching my 12 year old daughter to shoot now and it helps with her ability to make consistent shots. Have one rifle setup up with the cosine indicator/bubble level as well but seriously doubt I will shoot at the distance anymore where I will use that feature but nice to have.

 

[LRNut]

Thanks for your response, I recently gotten back into medium and long range shooting, a few years ago. Due to my inability to shoot more than 1-2 times a month, less in bad weather, or this covid-19 issue that has closed my range down for two months now, I agree with your assessment. My hunts are pricey endeavors now and the cant issue is one variable that I can address fairly inexpensively with the bubble levels, I have put them on all of my hunting rifles and now use an Atlas bipod for hunts. Is the bubble level perfect nope, but it keeps my repeatability in check(due to my previously undetected cant issues, was I canting repetitively the same, sometimes), plus teaching my 12 year old daughter to shoot now and it helps with her ability to make consistent shots. Have one rifle setup up with the cosine indicator/bubble level as well but seriously doubt I will shoot at the distance anymore where I will use that feature but nice to have.

Forget the cosine indicator; get a SIG Kilo 2400 ABS. You don't have time to do all the math when hunting, and even if you do you can make mistakes. The Sig Kilo 2400 ABS corrects for inclination/declination. Will see how well it compensates for altitude on my Colorado property this weekend, which is about 8000 feet.

 

[antelopedundee]

If you use a Pic rail for your scope base there are bubble levels that you can attach direct to the Pic rail. Like this one on eBay.

I ended up getting one like this .

I set it close to the power selector ring. Took an empty Kleenex box and cut a couple notches in it. Next I took it outside and set the scope in the notches and turned it until the vertical crosshair was aligned with the straight edge of a building. I could have used a plumbline too. Then I adjusted the level until the bubble was situated between the lines when the vertical crosshair was vertically aligned. So when I go to the range, I'll know when the rifle is not level, because it won't be the scope.

The drawback to a lot of the bubble levels is that the bubble doesn't fully fill the space between the lines leaving one to guess when things are actually level. There is at least one Pic rail available with a built in level, but it's hard to see in use so mostly useless IMO.

 

[An Idahoan]

Your brother should test his theory. Go mount a scope canted a bit. Zero at 100. Shoot 3 shots. Run up 20moa on same target. Shoot 3 shots.

I am not certain how much he cants his rifle stock, but I know his his scope reticle is plumb (repeatably so due to his bubble level). I am certain that our mutual friend has a pronounced cant to his stock and he rings steel out to 1300 yards all the time. It is not a theory. I know exactly where/how my thinking went wrong when I used to think the bore and optical axis needed to be plumb. One day I may record a trip out on the range, but for now - I have a comfortable system that I know works. In the meantime, I am merely trying to help others as my brother tried to help me. Based on your signature, I am just trying to pass on wisdom!

 

[huntintoo]

I have a Springfield that I use on my .308 that has the bubble/level at the bottom of the cross hairs! Wish it was like that in all my scopes!
Springfield is not making scopes anymore, so I found another used one and haven't decided what to mount it on yet?
The bubble made a difference in my shooting abilities.